v2.4.0.6

Stock Repurchase Program - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended			3 Months Ended
	May 25, 2011	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2010	Apr. 30, 2012 Accelerated Share Repurchase Agreement	Jan. 31, 2012 Accelerated Share Repurchase Agreement	Oct. 31, 2011 Accelerated Share Repurchase Agreement	Jan. 06, 2012 Accelerated Share Repurchase Agreement	Sep. 30, 2011 Accelerated Share Repurchase Agreement
Stock Repurchase Program [Line Items]
Stock repurchase program authorized amount	$ 500.0	$ 500.0
Stock repurchase program remaining authorized repurchase amount		272.4
Accelerated share repurchase agreement amount								40.0	75.0
Stock repurchase program prepayment									75.0
Initial number of shares received from accelerated share repurchase agreements							1,710,376
Initial share value							41.7
Remaining balance of value or shares to be settled							$ 33.3
Number of shares to settle equity forward contract					1,368,616	1,105,457
Average purchase price per share		$ 29.64	$ 26.53	$ 22.43	$ 29.23	$ 26.64

X

- Definition

Accelerated share repurchase agreement amount.

+ References

No definition available.

+ Details

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Namespace Prefix:	snps_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Accelerated share repurchase initial share delivery amount.

+ References

No definition available.

+ Details

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Namespace Prefix:	snps_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Accelerated Share Repurchases Settlement Of Equity Forward.

+ References

No definition available.

+ Details

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Namespace Prefix:	snps_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Details

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Namespace Prefix:	snps_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Stock repurchase program prepayment.

+ References

No definition available.

+ Details

Name:	snps_StockRepurchaseProgramPrepayment
Namespace Prefix:	snps_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount of cash payment to or cash receipt from the bank; or the stock issuance to or stock received from the bank in the settlement of the accelerated share repurchase agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 99-7

-Paragraph 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section B

-Paragraph 11A

-Chapter 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3



Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

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Data Type:	xbrli:sharesItemType
Balance Type:	na
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X

- Definition

The amount authorized by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

The remaining repurchase amount authorized by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Total cost of shares repurchased divided by the total number of shares repurchased.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section B

-Paragraph 7

-Subparagraph b

-Chapter 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration